This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In the last ten years influenza carried by birds has taken a worldwide stage as a zoonotic pathogen with potentially devastating effects on world health (Holmes et al., 2005). Migratory birds, implicated in the spread of Asian H5N1 influenza, cover vast distances twice a year, coming into contact with a wide range of habitats, many of them part of human habitats. While a great deal of work remains focused on common human subtypes of influenza which cause thousands of deaths worldwide each year, it is now realized that many of the common strains in humans and other animals may have derived from the vast pool of viruses circulating in wild birds. Unfortunately, despite years of surveillance in wild birds the scientific community understands very little about the natural history and ecology of infection and transmission in wild birds (Causey and Edwards, 2009). The ecology of the influenza virus encompasses a broad understanding in three realms: 1) the transmission of virus in space and time between individuals (epizootiology) 2) the biogeochemical environment in which the virus resides and 3) the host-pathogen interface (encompassing the dynamics of infection within the avian host). In this project, we propose to better understand the pathogenic potential of organisms and toxicants as they interact in the intestine via basic chemistry (e.g., elements analyses, proximate composition), diagnostic methods (e.g., immunoassays, morphology/histology), and molecular microbial ecology (defining the biotic environment) and pathogenesis.